Commonly used flat display panels include Liquid Crystal Display (LCD) panels and Organic Light-Emitting Diode (OLED) display panels. An LCD display panel or an OLED display panel includes an array substrate. The array substrate includes a plurality of pixel circuits arranged in an array and consisting of thin film transistors (TFTs), and each pixel circuit corresponds to one subpixel unit. Thin film transistor, as a control switch of a display panel pixel, is directly related to a developing trend for high-performance flat display panels.
Currently, a thin film transistor in an array substrate includes a gate, a source and a drain as well as an active layer formed between the source/drain and the gate. In order to improve performance of a display panel, it is necessary to improve carrier mobility of the active layer as much as possible. Diamond single crystal has a high carrier mobility and good TFT properties, and is a potentially excellent material for the next-generation TFTs. However, due to the high mobility of this material, leakage current of the TFT device is large, which has an adverse impact on operation characteristics of the TFT device. If such an impact lasts for a long period of time, TFT characteristics will deteriorate and quality of products will decline.